This invention is directed toward a system for supplying fuel to an engine and, more particularly, to a fuel supply system in which acceleration enrichment is provided in response to a sensed engine transient condition representing an increasing power demand of the engine.
During accelerating conditions of an internal combustion engine, lean air/fuel ratio excursions in the air and fuel mixture drawn into the cylinders will typically result if the fuel supply rate to the engine is not increased beyond the normal steady state running fuel requirements. In order to prevent the lean excursions in the air/fuel ratio of the mixture drawn into the engine during an acceleration maneuver of the engine, numerous forms of acceleration enrichment systems have been proposed that increase the fuel supplied to the engine during the transient engine condition.
One known acceleration enrichment system provides enrichment in response to transient engine operating conditions as represented by changes in the throttle position controlling the air input of the engine. Typically, the amount of fuel increase is dependent upon factors including coolant temperature and engine speed.
In this form of acceleration enrichment system, at low engine speeds it is desirable to respond rapidly to a sensed transient condition represented by a change in the throttle position in order to provide satisfactory engine operation. However at higher engine speeds, acceleration enrichment provided by a rapid response to a change in the throttle position results in excessive fuel being supplied to the engine. At the higher engine speeds, it is desirable to respond more slowly to a sensed transient condition represented by a change in the throttle position. However, at the lower engine speeds, a slow response to changes in the throttle position results in excessive acceleration enrichment fuel being provided to the engine too late.